In conventional film-screen radiography, an object, such as a patient's body part, is exposed to x-rays projected through the object to the film-screen to produce a latent x-ray image of the object in the film. The film is then processed with chemicals or heat to produce a visual x-ray image for analysis by a medical practitioner. Computed radiography (CR) eliminates the necessity of developing film with chemicals or heat by producing a latent x-ray image in a storage phosphor which is subsequently scanned to produce a digital radiographic image that can be viewed on an electronic display. The storage phosphor can then be erased and reused.
Typically, the storage phosphor is contained in a light tight cassette. The cassette containing an exposed storage phosphor is presented to a storage phosphor reader (also referred to as a CR reader) where the exposed storage phosphor is removed from the cassette, scanned to produce a digital image, erased, and replaced in the cassette. It is desirable that the cassette interface of the CR reader be capable of handling different sized cassettes, accurately centering them, minimizing skew errors, and providing storage phosphor removal from and replacement in the cassette that is simple, automatic and accurate.